I never thought that in my lifetime I would still find myself explaining to people that fats just don’t make you fat. But I am still explaining it to a lot of people. So in an effort to spread the word, I’m writing a post about fats.
What are fats, you ask? The good ol’ Wiki tells us that fats consist of a wide group of compounds that are generally soluble in organic solvents (like acetone and ethanol) but not soluble in water. That makes sense, right? You could use nail polish remover to get rid of an oil drip, and water and oil in the same container will separate into two layers. There are two main categories for dietary fats: “oils” and “fats”. These are not scientific terms, but generally oils remain liquid at room temperature while fats are solid at room temperature. Already you can separate some of these in your mind: olive oil, oil; butter, fat; crisco, fat; sesame oil, oil. But really what makes this difference between the two types of dietary fats? It is their saturation.
In order to explain fat saturation, I’ll have to talk a little bit about fat molecules. Please excuse this nerd while she giggles with delight.
This is a very basic picture of a fat molecule. On the left in blue is a glycerol molecule, which consists of carbon (C) and hydrogen (H), and the three similar-looking tails are fatty acids. These consists of a carboxyl group (carbon and two oxygens) and a chain of carbons and hydrogens. Carbon, as an atom, has four valence electrons; in other words, carbon may bind with four other atoms. But it does not have to. In the case of the last fatty acid chain, there is a double bond between two of the carbons, which means they are sharing two valence electron pairs. When each carbon in a chain of a fatty acid is holding as many hydrogens as possible (meaning it shares one valence electron each with two hydrogens and two adjacent carbons) then the chain is said to be saturated. When there is one or more double bonds between carbons because there are not two hydrogens bonded to each carbon, the chain is said to be unsaturated. Fats, which are solid at room temperature, are saturated fats, and oils, which are liquid at room temperature, are unsaturated. Because of this difference in molecular arrangement, saturated fats tend to hold a larger amount of energy (read calories), but both are able to be processed naturally by the body.
Trans fats, on the other hand, are a different story. They are a different isomer of the tradition fatty acid molecule, which means they contain the same number and types of atoms but are arranged differently. This means they cannot be processed by the body like other fats (simply because they don’t stack and flow through properly). The consumption of trans fats has been linked to coronary artery disease.
I say all of that to say this: Your body needs fats.
Fats, both saturated and unsaturated, are crucial to satiation. Eating fat with a meal triggers your brain that you are full, and you will remain full longer.
Fats also maintain healthy cell function, keeping everything lubricated.
Fats keep your skin smooth and hair shiny and healthy.
Fats are necessary for the absorption of vitamins A,D,E, and K.
Plus, fats sometimes just make a meal more pleasant. Think of bread and butter, or a salad with olive oil and vinegar. Fat keeps us happy, not fat.